1. Field of the Invention
The invention relates to an electronic toll collection method and system, more particularly to a two-way packet radio-based electronic toll collection method and system which utilizes multipoint-to-point communication to exchange toll collecting and payment information.
2. Description of the Related Art
Presently, most of the toll collecting functions in a conventional manual toll collection system are implemented with the physical presence of toll collectors. Such a system can only process about 900 vehicles per hour. As the vehicle approaches the toll booth, it reduces its speed, pays the toll, then speeds up and leaves. This system tends to cause congestion around the toll booth, stalling of traffic flow, exacerbation of air pollution and results in waste of time and energy. In order to tackle these problems, many companies and research agencies in industrialized countries have devoted their research and development efforts on the development of electronic toll collection systems.
The underlying principles behind the toll collecting functions of the different electronic toll collection systems developed all over the world are similar. Toils can be collected in the following ways:
(1) deducting directly the tolls from an electronic card installed in the vehicle by radio wave communication;
(2) deducting the tolls from the balance of an electronic card, which balance being recorded by a control computer; or
(3) using a control computer to collect the tolls via data of an electronic card of an In-Vehicle Unit and transmitted wirelessly by the latter, and deducting the tolls from the electronic card after the data transmitted by the In-Vehicle Unit have been verified. To avoid any fraudulence, vehicle-type detectors and photographic equipments may be added to the system. For further protection against toll evasion, the system may incorporate an alarm device that can alert the motorist of low card balance and that is linked to an automatic control system and to a computer telecommunication equipment.
Different traffic congestion problems require different solutions in electronic toll collection systems. The lane-based toll collection system functions well in places that have a relatively low traffic volume but may not apply in areas where heavy traffic occurs regularly. In a lane-based toll collection system, a sensor is installed in every lane to initiate point-to-point communication with the vehicles that pass through the corresponding lane in order to achieve the toll collecting function.
The following are brief descriptions of the different electronic toll collection systems developed in different countries:
1. The AMTECH system developed in the. United States This system operates in the following manner:
a. As a vehicle passes by a sensor that is disposed underneath the surface of the highway, signals are transmitted to equipment installed on the roadside. PA1 b. The antenna on the roadside then transmits radio waves to the vehicle via point-to-point communication. Data stored in a tag of the vehicle are transmitted to the antenna in order to enable the equipment on the roadside to verify the validity and balance of the tag. PA1 c. A discrepancy in the data will trigger alarms or will cause the activation of a camera so as to take a picture of the vehicle. PA1 d. If the balance is too low, the system will alert the motorist with the use of a red lamp. PA1 e. If everything is in good order, the system will signal the motorist to pass through the toll booth. The tolls can be deducted from the card at this stage. PA1 a. A reader installed on the roadside transmits control signals every 10 msec. PA1 b. As soon as the machine detects the arrival of a vehicle, it will transmit pulse signals, inclusive of the code of the lane, to a transponder on the vehicle via point-to-point communication. PA1 c. Upon receiving the signals from the reader, the transponder on the vehicle will transmit signals, inclusive of the vehicle model and identification, to the reader via point-to-point communication. PA1 d. The reader will process the signals received from the vehicle and transmits the results to the transponder in order to deduct the tolls therefrom. PA1 a. A first communication tower located 1/2 mile away from the toll booth transmits continuously one-way signals to inform a transponder of the vehicle to prepare payment of a certain amount of tolls. PA1 b. The transponder checks its own memory to see if there is a sufficient balance. In case the balance is insufficient, the transponder will alert the motorist with the use of a beeper and warning lamps to instruct the motorist to switch to other lanes where tolls can be collected manually. PA1 c. If there is a sufficient balance, the motorist can continue to pass through the lane. The transponder then transmits signals to a second communication tower via point-to-point communication with regards to the vehicle ID and the balance of the transponder. As the data pass from a reader to a lane controller, tolls will be deducted from the transponder. PA1 d. Finally, after the tolls have been paid, the code of the lane and the card balance will be stored by the transponder of the vehicle in its memory. PA1 a. As a vehicle passes by a sensor that is disposed underneath the surface of the highway, the sensor will transmit signals to notify a control computer of the lane. PA1 b. The sensor also activates a photographic equipment to take a picture of the vehicle. The picture is converted into an electrical signal and is stored in an integrated circuit in order to enable the system to identify the vehicle model. PA1 c. An antenna located on the roadside will transmit signals to a surface acoustic wave (SAW) card of the vehicle. The card is not equipped with a signal transmission mechanism but can reflect surface acoustic wave to a card reading machine. PA1 d. The card reading machine decodes the number of the card and transmits this number to the control computer. PA1 e. The control computer then obtains the user's status from its database and performs the following tasks: PA1 e1. If the vehicle does not carry an SAW card or if the card is invalid, the system will activate a red lamp or will set off an alarm. In the meantime, the picture of the vehicle will either be printed out for summons or transmitted to the next toll booth for interception. PA1 e2. If the card is valid but has an insufficient balance, the system will activate a yellow lamp to alert the motorist while recording relevant data in the meantime. PA1 e3. If the card is valid and has a sufficient balance, the system will activate a green lamp and record relevant data. PA1 a. A vehicle is equipped with an In-Vehicle Unit and a detachable smart card with a microprocessor controller and a communication interface. Some cards can even come with detecting components. PA1 b. The roadside network is equipped with a central control unit and signal poles. As the vehicle passes the warning zone, the signal poles on the side of each lane will transmit signals to the In-Vehicle Unit via point-to-point communication. PA1 c. The system will activate a congestion measurement device to begin two-way communication to exchange relevant information with regards to the toll amount due, the parking space available, the possible length of delay, etc. PA1 d. At the same time, an On-Board Unit will be triggered to collect tolls by deducting the amount from the smart card. PA1 e. The data received by the vehicle can be stored in the memory of the communication unit of the vehicle. PA1 f. The In-Vehicle Unit will generate audio or visual warning signals to inform the motorist about every procedure. After the tolls have been paid, the new balance will be displayed. PA1 g. Tolls can be fixed or adjusted to reflect peak or non-peak condition rates. PA1 a. A roadside antenna transmits a low power radio wave to allow only one vehicle to receive the same. PA1 b. As a vehicle passes by, data stored in an electronic card of the vehicle will be transmitted to the roadside antenna via reflection of the radio wave. PA1 c. The system compares the received data with those stored in its database. PA1 d. If the electronic card turns out to be invalid or has an insufficient balance, the system will set off an alarm and activate photographic equipment to take a picture of the delinquent vehicle for use as evidence. PA1 e. If the electronic card is valid, the system will activate a green lamp and deduct the tolls from the card. PA1 a. A sensor of the system detects the entry of a vehicle into a divided lane of the toll area. PA1 b. The system will take a picture of the vehicle and store the picture for model verification. PA1 c. In the divided lane, a detached IC card in the vehicle conducts point-to-point communication four times to transmit data in the card to a roadside antenna. PA1 d. A card processing equipment on the roadside will process the received signals to ensure that the card is valid and that there is a sufficient balance before the tolls can be deducted from the card. The data is updated and transmitted to the IC card and to other relevant entities. PA1 e. A roadside display device will show the amount of tolls paid and the new balance. PA1 f. If the major antenna is inoperable, a back-up antenna is employed to handle emergency communication. PA1 a. Vehicles are equipped with a smart card and a card reading system. PA1 b. The smart card is plugged in as a vehicle enters a restricted area. PA1 c. As the vehicle passes a control point, an antenna will transmit signals via point-to-point communication to activate the In-Vehicle Unit so as to enable the latter to process incoming data and transmit reply signals to the roadside unit. PA1 d. A roadside processor then verifies the validity and balance of the card. PA1 e. If everything is in good order, tolls are deducted from the card. Otherwise, the motorist will receive warning signals from light emitting diodes (LED) or beepers. Data is then sent to a central computer for further action. PA1 f. If the system cannot detect the presence of a valid card reading system, a camera is activated to take a picture of the delinquent vehicle. PA1 providing a communication tower which transmits continuously downlink communication packets that contain information regarding available uplink communication channels; PA1 installing an in-vehicle unit in each vehicle passing along the highway to receive the downlink communication packets, the in-vehicle unit selecting one of the available uplink communication channels; and PA1 exchanging toll collecting and payment information wirelessly between the in-vehicle unit and the communication tower via the available uplink communication channel selected by the in-vehicle unit and a downlink communication channel corresponding thereto.
2. The AT&T system
This system operates in the following manner:
These two systems participated but failed in a road test held in the United States.
3. The AT/COMM system
This system operates in the following manner:
4. The SAIC system
This system combines the traditional toll collection equipment, the vehicle recognition equipment and the communication equipment. Since tolls are to be paid in coins, and since communication is lane-based, speed limits have to be imposed on vehicles passing through the toll booth. This constraint tends to slow down the traffic and can cause traffic jams. Besides, this system only provides one-way communication capability which cannot meet the requirements of an Intelligent Vehicle Highway System (IVHS).
5. The 3M system developed in the United States
This system operates in the following manner:
Note that this system conducts one-way communication via reflection. Thus, it cannot accommodate the requirements of IVHS.
6. The PAMALA system developed in Europe
This system operates in the following manner:
7. The PREMID system developed by Philips of Holland and CSEE of France
This system operates in the following manner:
8. The Automatic Toll Collection System developed by Panasonic of Japan
This system operates in the following manner:
9. The ERP system developed in Holland
This system is used in Singapore to control traffic entering the downtown area. The system operates in the following manner:
Note that the different electronic toll collection systems described beforehand are lane-based. Furthermore, the exchange of data and card verification procedures are conducted via point-to-point communication. This will impose a certain speed limit on the vehicles passing through the toll booth and require a certain distance to be kept between two vehicles on the same lane. In the lane-based system, the toll collection system is installed on every lane. Since data exchange and toll collecting functions are to be carried out within a short distance, speed limits will be imposed on vehicles passing through the toll booth. These systems may work well in countries where the traffic density is low, but will not function well in over-congested areas where two vehicles may travel the same lane and compete for the same communication unit.